Fuel-injection nozzle valve



May 19, 1942. e. EICHELBERG FUEL-INJECTION NOZZLE VALVE Filed April 18,1959 VIVVENTOR A GUSTAV E/Cl/ELBL'RG ATTORNEYS.

Patented -May 19, 1942 UNITED STATES PATENT OFFICE 2,283,725FUEL-INJECTION NOZZLE VALVE Gustav Eichelberg, Zurich, SwitzerlandApplication April 18, 1939, Serial No. 268,602

In Germany April 11, 1938 Claims. (Cl. 299-'-107.6)'

I. Fuel-injection valvesare known which operate with a pressureaccumulation of fuel. .Such accumulation can be arranged to take placebelow auspring-loaded piston which is raised by the fuel or,alternatively, the actual compression of I the fuel itself can be used,this compression taking pIace-in a chamber arranged near to andconnected with the injection nozzle with which I ;.-,i s associated thevalve seat onto which a needle yalveis pressedby the action of a valvespring.

The present invention relates to the second of turelifting of the valveneedle against the force of the valve spring, under the action of thepres- .sure of .the fuel delivered from the pump, by causing this fuelpressure to act upon the end of the needle remote from the valve-seat.In this way the injection is initiated by relieving the pressure in thefuel-supply pipe and thereby relieving the pressure on the upper end ofthe needle. The pressure of the fuel to be injected acting on the lowerend of the needle then raises the latter, allowing the injection totakeplace.

This injection continues until the pressure of the accumulated fuel hasfallen to so low avalue that the valve spring depresses the needleagainst the falling pressure of the fuel onto the valve-seat.

.It is evident that precautions must be taken that the relief of thepressure on the outer end of the needle, which arrests the injection,does not also diminish the pressure in the pressure acpressure in theaccumulating chamber is only relieved through the throttling passage ina very slow and gradual manner which does not substantially afiect theinjection.

The foregoing systems suffer however, from a number of drawbacks.

In the first place, the chamber at the upper end of the needle is ofdisproprotionately large size owing to the valve spring being located init.

The volume of fuel present in this chmber must,

after every drop in pressure, be again raised from zero-pressure to theinjection pressure and to effect this a large, additional volume offuelhas like low-viscosity fuels. I

to be delivered by the pump. This additional volume of fuel may, whenthe apparatus is of small dimensions be many times, the volume of thefuel normally injected. Furthermore, the losses through leakage betweenthe stem of the needle and the bearing therefor, even when the surfacesare a ground fit, are very considerable, more especially when operatingwith petrol and Lastly, the return flow losses already referred to asoccurring when a throttling passage is used, while depending on theconstruction of the valve, are not o insignificant as'not to exercise adetrimental efiect on the operation of the apparatus.

It is an object of the invention to provide a fuel-injection valve inwhich the above drawbacks are avoided, this being done mainly byreducing the size of the upper chamber.

In Figure 2 of the accompanying drawing, a construction according to theinvention is shown in'greater detail by way of example, while in Figme 1a knownconstructional form of a fuel-injection valve is shown for thesake of comparison and to facilitate the understanding of the invention.

The fuel injection valve according to the invention comprises a chamberin which pressure accumulation of the fuel takes place, a valve adaptedto close the outlet from the chamber, a spring pressing the valve on toits seat, and a second chamber intowhich part of the valve extends andinto which fuel is adapted to be admitted under pressure so as" to acton the valve to press the latter towards its seat, the said spring beinglocated in the pressure accumulating chamber.

The valve is preferablyarranged so that, when raised from its seat, apart of it co-operates with a fixed member to close the passage throughwhich fuel is delivered to the pressure accumulating chamber from thesecond chamber.

According to a further practical feature of the invention arrangementsare made that, when a throttling passage, and not a non-return valve, isprovided between the second chamber and the 'pressure accumulatingchamber, this throttling passage-is arranged in such a way as to put thepressure accumulating chamber in communication with that section of thesecond chamber which, during the injection or when the needle is lifted,is shut off from the fuel-pipe by the valve member which limits thestroke of the needle.

In this way, not only is the back-flow loss reduced to a very greatextent because any such back-flow is possible only during the briefmoment when the needle is lifted, but, in addition to this, a dimcultynow to be explained is successfully overcome.

In the case of pressure accumulating valves making use of pure liquidaccumulation, there is the well-known difficulty that the proportion ofthe idle-running to the full-load quantity is approximately 1 to 6, sothat, by virtue of the compressibility of the fuel, the pressure rise inthe accumulating chamber above the residual pressure at the time of theclosing'of the valve varies in the proportion 1 to 6 for idle-runningand full load respectively. This tends to produce either a very highfuel-pressure with full-load, when the pressure accumulatingchamber iscomparatively small, or, too small a rise in pressure when runningidle-if the pressure accumulating chamber is comparatively large. Thissmall rise in pressure when running idleis not suflicient to overcomethe difference between the closing and opening pressures of the needle.(Cf. Dr. Ing. G. Eichelberg On means for compressorless fuel injection.V. D. I. Zeitschrift vol. 70, Nr. 32, August 7, 1926, page 1079 et.seq.)

As a resultof the alteration of the position of the throttling passageas described above, an additional quantity of fuel isabstracted from thepressure accumulating chamber and will flow back through the throttlingpassage, though only during the moments when the needle is openingandclosing and not when the needle is in its raised or open position.This back-flow does not, therefore, coincide with the injection periodof the needle. It is of approximately equal volume for full-load andidle running. If, for instance, the back-flow volume is assumed to beequal to the volume injected when running idle, then the ratio of thetotal quantity to be stored when running idle to that to be stored atfull load is 1+1 to 6+1, or 2 to 7, and is no longer 1 to 6. The risk ofany interruption of the injection with partial load can thus beeliminated.

In the known form according to Figure 1, fuel is fed to the valve 1through the pipe 2. The pressure accumulating chamber 5 is here suppliedthrough the pipe 2, and the fuel is admitted to the second chamber 6through the pipe 4. A non-return valve 3 may be provided which closeswhenever the pressure in the fuel pipe drops or, alternatively, thechamber 5 may be connected with the chamber 5by means of a throttlingpassage l. The valve closing spring 8 is located in the chamber 6. Theoperation of this type of nozzle valve is well known and its drawbackshave already been pointed out.

In the form of construction according to the invention shown, by way ofexample, in Figure 2, the spring 8 is arranged in the accumulatingchamber 5 below the bore or bearing for the valve needle 9, which boreis formed in the valve body I. A throttling passage 1 is providedbetween the chamber 5 and the small space above the stem of the valve,the passage opening into said space at such a. point that when theneedle 9 is raised, it acts as a valve to cut off the throttling passage1 from the fuel pipe. It will be noted that the effective surface of thevalve head in its closed position on which the hydraulic pressure isupwardly directed is greater than that on which the hydraulic pressureacts downwardly The manner in which this fuel-injection valve operatesis, briefly, as follows:

The fuel enters through the pipe 2 into the upper part of the bore forthe needle 9 which constitutes the second chamber. The fuel then passesinto the accumulating chamber 5 by way of the throttling passage 1.Wheneverthe pres,- sure in the fuel feedplp drops, the needle 5 is, inconsequence, lifted by reason of the differential under surface of thevalve head and shuts oil. the throttling passage from the fuel pipe. Thefuel is then injected into the engine cylinder through the apertures H.As soon, however, as the pressure in the storage chamber 5 ,has fallensufficiently, the needle 9-is returned to its seat by the action of thespring 8. In this way the communication between fuel-pipe, throttlingpassage and accumulating chamber is again established and the latter isrefilled, that is, the pressure therein again raised, the sequence ofoperations being repeated when the pressure in the fuel pipe againfalls.

The correct positioning of the throttling passage is of great importancefor the operation ofthe device of the invention. Thus, for example, anyarrangement in which the throttling passage connects the chamber 5. withthe pipe 2 g at a point above the upper limit of the stroke of the valvestem isundesirable because there is no closing of .the passage when theneedle is raised. 1 There are many modified forms ,of construction thatmight be specified and which fall within the scope of the invention; anddonot depart from its fundamental principle. Thus for in,- stance, thethrottling passage might be replaced by a different system ofcommunication such as grooves, channels and the like, or the needle stemmight evenmerely be made a loose fit in the bore.

Having now particularly described and ascertained the nature of. my saidinvention and in what manner the same is to be performed, I declare thatwhat I claim is:

1. A fuel injection nozzle having a chamber in which pressureaccumulation of the fuel takes place, said chamber being provided withan out let, a valve element adapted to close said out let, a secondchamber into which part'of the valve element extends and into which fuelis adapted to be admitted under pressure so as to act on the valveelement to press the same towards its seat, and a passageway leadingfrom the accumulation chamber and so constructed and arranged as to bein communication with the second chamber when the valve element is inits closed position, said valve element in its a part of said valveelement extending into said second chamber the fuel under pressure insaid second chamber acting on the valve to urge it into its closedposition, and means normally connecting the two chambers to feed fuelfrom the second chamber to the accumulation chamber and remaining openduring the period that the valve is closed, said fuel feeding meansbeing so constructed and arrangedas to be rendered inchamber to theaccumulation chamber, said fuel f feeding conduit being so constructedand aroperative when the valve is lifted by the fuel under pressure inthe accumulation chamber upon fall of pressure in the second chamber.

3. A fuel injection nozzle as claimed in claim 2, wherein the secondchamber comprises a bore in the valve body receiving snugly the stem ofthe valve, said connecting means comprising a throttling passagewayopening into the accumulation chamber and leading from an apertureopening into the bore intermediate the end of the valve stem when thevalve is in the closed position and the opposite end of the bore.

4. A fuel injection valve having a chamber in which pressureaccumulation of the fuel takes place, said chamber being provided, withan outlet, a needle valve controlling said outlet and located within theaccumulation chamber, a second chamber coaxial with the outlet, thevalve having a stem passing into said second chamber, a conduit forsupplying said second chamber with fuel under pressure, a throttlingpassageway leading from the pressure accumulating chamber to the secondmentioned chamber and opening into said latter chamber at a point whichbecomes covered by the stem of the valve when the valve is opened by thepressure of the fuel within the accumulation chamber-upon fall ofpressure in the fuel conduit.

5. A fuel injectionvalve as set forth in claim 4, including a springlocated in the pressure accumulation chamber, and acting to urge thevalve to its closed position.

6. A fuel injection valve set forth in claim 4, wherein the secondchamber constitutes a cylindrical bore within which the stem of thevalve snugly fits.

7. A fuel injection valve comprising a body having a chamber in whichpressure accumulation of the fuel takes place, said chamber beingprovided with an outlet, a solid unbored needle valve controlling saidoutlet, a spring located in the chamber and acting on the valve to urgeit to the closed position, said valve having a cylindrical stem; acylindrical bore coaxial with the outlet and extending from the pressureaccumulation chamber, the stem of the valve being slidably receivedwithin said bore; a fuel conduit connected with the bore beyond the endof the valve stem and adapted to charge fuel under pressure into saidbore, and a passageway connecting the pressure accumulation chamber withthe portion of the bore unoccupied by the valve stem when the valve isin the closed position, and opening into the bore at a point whichbecomes covered by the valve stem when the valve is lifted to openposition.

8. A fuel injection valve comprising a chamber, an inlet for the supplyof fuel directly into said chamber,- an accumulation chamber in whichfuel pressure is built up, said accumulation chamber being provided witha valve seat and with an outlet leading from said valve seat, a valveelement having a head of reduced crosssection adapted to control saidoutlet, a spring located in the accumulation chamber and positioned tourge the valve element against its seat, the pressure of the fuel in thefirst mentioned chamber acting on the valve element to urge it to itsclosed position, and a conduit connecting the two chambers to feed fuelfrom the first ranged as to be closed when the valve is lifted by thefuel under pressure in the accumulation chamber. i

9. A fuel injection nozzle for combustion engines, said nozzle having achamber in which pressure accumulation of the fuel takes place, saidchamber having an inlet for fuel under pressure and provided with anoutlet, a pressureoperated valve element having a head adapted to closethe outlet from the chamber, a spring pressing the valve head onto itsseat, a second chamber into which part of the valve element extends andinto which fuel is adapted to be admitted under pressure so as to act onthe valve element to press the valve head towards its seat, the.pressure in said pressure accumulating chamber acting to open the valve,the said spring and valve head being located in the pressureaccumulating chamber, and said accumulating chamber being sufiicientlylarge to effect discharge through said outlet of the amount of fuelrequired for full load operation of the combustion engine upon reductionof the fuel pressure acting on the valve element in the second chamberand consequent opening of the valve element, and a passageway betweenthe chambers normally serving to deliver fuel from the second chambertothe inlet of the pressure accumulating chamber and connecting the twochambers continuously while the valve is closed, the valve element beingso constructed and arranged that when raised from its seat, a part of itacts to close said passageway.

10. A fuel injection nozzlefor combustion engines, said nozzle having achamber in which pressure accumulation of the fuel takes place,

- said chamber having an inlet for fuel under pressure and provided withan outlet, a pressureoperated valve element having a head adapted toclose the outlet from the chamber, a spring pressing the valve head onto its seat, a-second 'chamber into which part of the valve elementextends and into which fuel is adapted to be admitted under pressure soas to act on the valve element to press the valve head towards its seat,the pressure in said pressure accumulating chamber acting to open thevalve, the said spring and valve head being located in the pressureaccumulating chamber, and said accumulating chamber being sufiicientlylarge to effect discharge through said outlet ofthe amount of fuelrequired for full load operation of the combustion engine upon reductionof the fuel pressure acting on the valve element in the second chamberand consequent opening of the valve element, and a passageway betweenthe chambers normally serving to deliver fuel from the second chamber tothe inlet of the pressure accumulating chamber, and a feed pipe fordelivering fuel to the second chamber, said passageway being ofthrottling dimensions and communicating with that section of the secondchamber which is cut off from the feed pipe upon reduction in thepressure in said pipe and movement of the valve element within saidsecond chamber to open valve position.

GUSTAV EICHELBERG.

